[Animal models of transmissible subacute spongiform encephalopathies]

The lack of suitable in vitro test explains the major importance of animal models in the study of Transmissible Spongiform Encephalopathies (TSE). Models using big animals are closer to natural situations, while solely rodent adapted models can be used currently in laboratories. Different scientific approaches based on the utilization of these models permitted to evidence the multifactorial character of TSE, with factors linked to the host and others linked to the TSE agents, also called prions. Prion protein (PrP) is the major host factor as it has been recently demonstrated by transgenetic studies. Among agent related factors, the notion of independant strains of TSE agents is now well established in inbred mice even if molecular studies have hitherto not been able to precise their exact nature. Although these models constitute powerful tools for the study of TSE, it has to be reminded that they can be far from natural situations.